The Triaxial Earthquake and Shock Simulator (TESS) is an experimental three-dimensional "shake table," that tests the ability of systems, facilities, and equipment to survive under realistic conditions of shock, vibration, and earthquake ground motion. Operated by the US Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) in Champaign, IL, TESS is a unique dual-mode shock and vibration test facility where engineers can assess the seismic, shock, and vibration vulnerabilities of buildings and equipment to develop methods for mitigating these vulnerabilities.

Many unique technology transfer efforts have been successful due to the team’s ability to overcome numerous challenges that allow the TESS to meet a wide spectrum of customer needs. As an example, the facility was asked to conduct vibration testing of an Ebola patient Transportation Isolation System (TIS) by the Defense Threat Reduction Agency (DTRA). These tests were intended to mimic the vibration environment generated by propeller rotations on a C-130 aircraft. The DTRA needed a leak-proof isolation system to prevent Ebola-infected patients and medical staff from contaminating the interior of aircraft while also withstanding the long duration, high-frequency vibrations on a C-130 in flight.

The ERDC-CERL team developed testing motions, protocols, and specimen anchoring methods to meet DTRA requirements and to accurately mimic the conditions that the TIS would be subjected to during real-life transportation. The equipment utilized for these tests is the Triaxial Earthquake and Shock Simulator. Unlike most projects done with the TESS platform, these tests required high frequency and high amplitude motions within narrow frequency bands, and the ERDC-CERL team devised an innovative method to iteratively modify power spectra profiles used to generate test signals that increased the high-frequency content the TESS system normally attenuates. This method allowed them to maximize the TESS performance for the required profiles.

ERDC-CERL also used the TESS to test a DTRA shock-isolation system to characterize the performance of the system. The higher frequency content shock records were reduced by the TESS and to a greater extent than the lower frequency content of those records. ERDC-CERL developed unique amplification functions that were multiplied by the drive signals, which successfully compensated for the frequency dependent reduction of these records.

The result of the project was that the TESS facility successfully met the needs of DTRA and the testing environment that was created achieved a critical step toward the development of the Transportation Isolation System that will enable safe transportation of medical staff, soldiers and other patients with highly infectious diseases.